1. Field of the Invention
This specification relates to a clothes dryer, and more particularly, to a clothes dryer having a heat pump and heat exchange means, the clothes dryer capable of enhancing energy efficiency by recovering waste heat to the maximum in correspondence to a capacity of the heat pump, capable of enhancing reliability by preventing overheating of a compressor and the heat exchanging means, and capable of shortening drying time.
2. Background of the Invention
Generally, a clothes dryer serves to dry laundry by introducing the laundry having been completely washed and dehydrated into a tub (drum), and by supplying hot air into the drum so as to evaporate moisture of the laundry.
The hot air supplied into the drum is discharged out with the moisture of the laundry. This high-temperature and humid air may be processed in various manners. According to a method for processing the high-temperature and humid air, the clothes dryer may be classified.
More concretely, the clothes dryer may be classified into a condensation type clothes dyer for condensing moisture included in air by cooling humid air, by making high-temperature and humid air heat-exchanged at a heat exchanger inside the clothes dryer, through circulation without exhaustion to the outside, and an exhaustion type clothes dryer for exhausting high-temperature humid air passing through a drum to the outside.
This clothes dryer will be explained in brief with taking the exhaustion type as an example. FIG. 1 is a schematic view of an exhaustion type clothes dryer in accordance with the conventional art. The clothes dryer comprises a body 1 having a door 2 on a front surface thereof, a drum 3 rotatably installed in the body 1 and having a plurality of lifters 4 protruding from an inner circumferential surface thereof, driving means configured to provide a rotational force to the drum 3, a heater 5 configured to generate hot air by heating sucked external air to a high temperature, a suction duct 7 communicated with a rear side of the drum 3 and configured to guide the hot air generated by the heater 5 to an inner side of the drum 3, a lint duct 8 communicated with a front side of the drum 3 and configured to guide humid air exhausted after a drying operation to an exhaustion duct 15, and a blower 13 installed at a rear side of the lint duct 8 and configured to generate a blowing force. At an entrance of the lint duct 8, installed is a filter 14 configured to filter foreign materials such as dust or naps from air discharged from the drum 3.
The driving means for rotating the drum 3 consists of a motor 10, a driving pulley 11 coupled to the motor 10, and a driving belt 12 connected to the driving pulley 11 and encompassing an outer circumferential surface of the drum 3. Once the driving pulley 11 is rotated by rotation of the motor 10, the driving belt 12 wound on the driving pulley 11 is rotated to rotate the drum 3.
A drying operation of the clothes dryer will be explained.
Firstly, an object to be dried such as laundry is introduced into the drum 3. Then, a drying operation is performed to operate the heater 5 and the motor 10 and to rotate the drum 3 and the blower 13. As the blower 13 is operated, external air is sucked to be heated by the heater 5. Then, the heated air is forcibly introduced, through the suction duct 7, into the drum 3 being rotated. Then, the heated air introduced into the drum 3 dries the laundry by evaporating moisture of the laundry, and then passes through the lint duct 8 and the exhaustion duct 15, sequentially to be discharged out in a humid state.
Generally, the exhaustion type clothes dryer has advantages that the entire drying time is shortened owing to rapid heating by the heater, and massive fabrications are possible. However, the exhaustion type clothes dryer has a disadvantage such as a large amount of energy consumption, since introduced air is heated only by the heater and then is discharged out. More concretely, the amount of energy lost without being used in a drying operation in the drum corresponds to 30˜40% of the entire energy, and the amount of energy exhausted through the exhaustion duct corresponds to about 80% of the entire energy. This may result in a great deal of wasted energy.
In order to solve this waste of energy, heat exchange means may be used to recover part of waste energy. However, in this case, the heat exchange means may be overheated due to a limitation of a capacity. Furthermore, a fan may be additionally installed so as to enhance heat exchange efficiency by supplying a large air volume. Especially, a compressor used in a heat pump serving as the heat exchange means may be overheated. In the case that the compressor is overheated, reliability of the dryer may be degraded, and compression efficiency of a refrigerant may be degraded. This may lower the entire heat exchange efficiency.
On the other hand, the condensation type clothes dryer has advantages that an exhaustion duct for exhausting air to the outside is not required, and energy efficiency is high. However, the condensation type clothes dryer has disadvantages that designing the heat exchange means is restricted according to a performance or a capacity since waste heat is partially recovered to be used as air to be supplied into the drum, drying time is long, and massive fabrications are not easy. Especially, in the case of drying time, it takes more about three times than in the exhaustion type clothes dryer.